The obvious answer is we don’t know. The parallel with 1981-83, when hard-left Bennism was at its peak, is fuzzy. True, the Liberals were weak, then, too, having been singed by their unhappy experience during the Lib-Lab pact. But, at least at the moment, there seems no prospect of Labour moderates setting up an SDP v.2.

Without the excitement of a new Alliance to dominate the centre-ground of British politics, it’s going to be a much tougher gig for Tim Farron and his seven Commons’ colleagues to get a hearing, no matter how attractive their more moderate, progressive vision might be.

Anyway, here’s how it starts (sorry, the rest of the piece is behind the Times paywall):